A dietary supplement is defined as a product intended to supplement the diet; they must bear or contain certain ingredients such as vitamins, minerals and herbs, and not contain other ingredients such as approved drugs.  In the United States more than 50% of the population admits to taking at least one dietary supplement daily. The most common reasons for using supplements are to enhance performance, increase energy, prevent nutritional deficiencies, and maintain health, immune function & strength.Researchers have studied a variety of dietary supplements as possible preventions and treatments for many different conditions and diseases.  The role of calcium in preventing osteoporosis and folic acid in preventing neural tube defects are well documented and have led to better education, supplementation, recommendationsand treatment.These successful discoveries have led to an abundance of research studying a wide variety of diseases and dietary supplements.  To date the research has led to promising and disappointing results, but the studies continue.  Since November is Lung Cancer Awareness Month here is a review of the most recent studies that looked at the role of supplements in the prevention and treatment of lung cancer.Earlier studies linked low levels of vitamin D to a higher incidence of cancer and less survival.   Recent studies continue to investigate whether vitamin D levels play a role in predicting, treating or determining the prognosis of various lung cancers.  A study conducted at an oncology treatment center found that 77% of the patients suffering from a variety of cancers (including lung cancer) had vitamin D levels below the predicted levels for an advanced stage of the disease, once again linking low vitamin D levels with cancer.  Investigators plan to continue the research process by analyzing what impact vitamin D supplementation has on progression, treatment and survival once they administer vitamin D replacement therapy.Another recent study at the University of Michigan found that an enzyme involved in breaking down vitamin D can predict lung cancer recurrence and survival.  Researchers suggest the enzyme interferes with the anti-cancer effects of vitamin D and when levels are high as in the case of certain kinds of lung cancer, survival rates are half the rate of patients with low levels of the enzyme.  Researchers hope to use the findings to determine if treating lung cancer patients with vitamin D could prevent or delay the return of the cancer.  Researchers will also work on determining a drug or treatment to block enzyme production and hopefully restore the anti-cancer effects of vitamin D in patients suffering from lung cancers that result in high levels of the enzyme.We are not suggesting that anyone suffering from lung cancer or at risk of developing lung cancer start taking large doses of vitamin D.  It is always important that any findings from research studies be duplicated in a larger patient population before recommendations are made.  This is particularly importantwith a compromised patient population such as those suffering from lung cancer.  This new research is promising and provides improved prognosis for lung cancer (and possibly other cancer) patients.What you may want to do with this information is get your vitamin D levels tested at your next checkup.  If low levels are detected your doctor may recommend a dietary supplement.  In the mean time eat and drink some fortified dairy products and go outside and enjoy some sunshine every day.